Setting an array using Ruby and Win32OLE

I'm trying to set an array property in a COM object using Ruby v1.93. Marshalling an array from COM into a Ruby array just works, but not in the other direction. How do I marshall a Ruby array into COM?

The property is contained in a .NET assembly:

namespace LibForRuby
{
   public class MyClass
   {
      public MyClass()
      {
         MyInt = 1;
         MyArray = new[] {2, 3};
      }

      public int MyInt { get; set; }
      public int[] MyArray { get; set; }
   }
}

My entire ruby script is:

require 'win32ole'

com_class = WIN32OLE.new('LibForRuby.MyClass')

puts 'Before:'
my_int = com_class.MyInt
puts my_int
my_array = com_class.MyArray
print my_array
puts

puts 'After:'
com_class.MyInt = 10
my_int = com_class.MyInt
puts my_int
com_class.MyArray = [20,30]
my_array = com_class.MyArray
print my_array

The output is:

C:\Ruby193\bin>test
Before:
1
[2, 3]
After:
10
C:/Ruby193/bin/test.rb:13:in `method_missing': (in setting property `MyArray': )
 (WIN32OLERuntimeError)
    OLE error code:0 in <Unknown>
      <No Description>
    HRESULT error code:0x80020005
      Type mismatch.
        from C:/Ruby193/bin/test.rb:13:in `<main>'

Try this:

puts 'After:'
com_class.MyInt = 10
my_int = com_class.MyInt
puts my_int
com_class._setproperty(
com_class.ole_method_help('MyArray').dispid,
[[20,30]], 
[WIN32OLE::VARIANT::VT_ARRAY]
)
my_array = com_class.MyArray
print my_array

Make sure to lookup the #_setproperty method at ruby-doc.org to see why your array is enclosed in an array and why the variant constant is inside an array.